[ POWERED TWO WAYS ] - Use batteries. Each book reading light runs on 3 x AAA batteries(not included). - USB Power. Detach the base from the book light and plug into any USB port such as computer ,mobile power supply | [ 360° FLEXIBLE NECK READING LIGHT ] Nexck flexes so you can position the small lamp right where you want it | [ BOOK CLIP ] Conveniently and securely clips to your book for hands free operation while readying | [ ON/DIMMER/OFF OPERATION ] Easy to operate. Press the button on the light head once for full brightness. Press again for softer light. Press a third time to turn the book light OFF | [ SMALL LIGHTWEIGHT & PORTABLE BOOK LIGHT FOR READING ] Only 2.0 oz. It’s small and lightweight. It can be completely folded flat and slim, portable for reading on the airplane, train, or backseat of car when travelling